Systems and methods for caching and serving dynamic content

ABSTRACT

A web server and a shared caching server are described for serving dynamic content to users of at least two different types, where the different types of users receive different versions of the dynamic content. A version of the dynamic content includes a validation header, such as an ETag, that stores information indicative of the currency of the dynamic content and information indicative of a user type for which the version of the dynamic content is intended. In response to a user request for the dynamic content, the shared caching server sends a validation request to the web server with the validation header information. The web server determines, based on the user type of the requestor and/or on the currency of the cached dynamic content whether to instruct the shared caching server to send the cached content or to send updated content for serving to the user.

PRIORITY CLAIM

This application claims priority to U.S. Provisional Application No.60/945,799, filed Jun. 22, 2007, and entitled SYSTEMS AND METHODS FORDYNAMIC SERVING OF CONTENT, the entire contents of which are herebyincorporated by reference in their entirety herein and should beconsidered a part of this specification.

FIELD OF THE INVENTION

The disclosure relates to caching systems, and, in particular, to theuse of shared caching systems for serving dynamic web content.

BACKGROUND

The benefits of caching systems are well known. Local client-basedbrowser caches may cache for one user and/or for one computer. Sharedcaching systems may cache content for multiple users, such as multipleweb users, and/or multiple computers. For web page servers, sharedcaching systems may save the server from having to deliver contentdirectly to each client. However, most shared caching systems rely on atime-based caching approach. A time duration is established for how longcached web pages can be relied upon with assurance to be current, andthe established time duration is used to determine a time that web pagesremain available in cache. For web page or other content servers withcontent that changes frequently, the benefits of caching may be rathersmall, as the cached versions of the web pages are expired from cachequickly.

SUMMARY OF THE DISCLOSURE

A web server and a shared caching server are described for servingdynamic content to users of at least two different types, where thedifferent types of users receive different versions of the dynamiccontent. A version of the dynamic content includes a validation header,such as an ETag, that stores information indicative of the currency ofthe dynamic content and information indicative of a user type for whichthe version of the dynamic content is intended. In response to a userrequest for the dynamic content, the shared caching server sends avalidation request to the web server with the validation headerinformation. The web server determines, based on the user type of therequester and/or on the currency of the cached dynamic content whetherto instruct the shared caching server to send the cached content or tosend updated content for serving to the user.

An embodiment of a system for providing access to dynamic web content isdescribed. The system includes a shared caching server configured toreceive a web page request from a user for access to a web page. The webpage request includes information about the requested web page and aboutthe user. The shared caching server includes a repository of cached webpages, including the requested web page. The cached web page includesheader information that identifies when the cached web page was lastmodified. The system further includes an origin server that stores acurrent version of the web page. The origin server is configured toreceive a validation request from the shared caching server forinstructions whether to send the cached version of the web page to theuser or to send a modified version of the web page to the user. Thevalidation request includes information about the user and about thecached version of the web page. The origin server further includes arequestor identification module configured to determine a user typeassociated with the request and a validation-header-based decisionmodule. The validation-header-based decision module is configured toreceive from the requester identification module an indication of theuser type associated with the request. The validation-header-baseddecision module is further configured to use the information about thecached version of the web page to determine if the cached version of theweb page is the current version of the web page, and to provide aninstruction for the shared caching server indicating whether to use thecurrent version of the web page or a modified version of the web pagefrom the origin server.

An embodiment of a method of serving web content is described. Themethod includes sending a version of a web page with a validation headerto a shared caching server for caching. The validation header allows acomputerized determination to be made as to whether the version of theweb page is a current version of the web page and as to a type of userfor which the version of the web page is suitable. The method furtherincludes receiving from the shared caching server, in response to a userrequest for the web page, a validation request comprising informationabout a user making the user request and information from the validationheader from the cached version of the web page. The method furtherincludes determining, based on the information from the validationheader and on the information about the user, whether to send to theshared caching server a response that includes a modified version of theweb page with a new validation header or a response that includes aninstruction to use the cached version of the web page; and sending theresponse to the shared caching server.

An embodiment of a method of serving cached web content is described.The method includes caching, in a shared caching server, a version of afirst web page that has a version identifier. The method furtherincludes receiving, at the shared caching server, a request from a userto access a current version of the first web page. The user may be fromone of two or more different user types, and users of different typesreceive different versions of the first web page. The method furtherincludes sending a first validation request to an origin server. Thefirst validation request includes information indicative of the versionidentifier and information about the user. The method further includesreceiving, at the shared caching server, a response from the originserver that includes a modified version of the first web page forsending to the user or includes instructions to send the cached versionof the first web page to the user. The response is generated by theorigin server, based, at least in part, on at least one of the setconsisting of: a determination of the user's user type and adetermination as to whether the cached version of the first web page inthe shared caching server is the current version of the first web page.If a modified version of the first web page is received by the sharedcaching server from the origin server, the method further includesproviding the modified version of the first web page to the user, and ifno modified version of the web page is received by the shared cachingserver, providing the cached version of the first web page to the user.

An embodiment of a computer-readable medium is described. Thecomputer-readable medium stores executable instructions that, whenexecuted by a processor, cause the processor to perform a method forserving web content. The method includes sending a version of a web pagewith a validation header to a shared caching server for caching. Thevalidation header allows a computerized determination to be made as towhether the version of the web page is a current version of the web pageand as to a type of user for which the version of the web page issuitable. The method further includes receiving from the shared cachingserver, in response to a user request for the web page, a validationrequest that includes information about a user making the user requestand information from the validation header from the cached version ofthe web page. The method further includes determining, based on thevalidation header information and on the information about the user,whether to send to the shared caching server a response that includes amodified version of the web page with a new validation header or aresponse that includes an instruction to use the cached version of theweb page; and sending the response to the shared caching server.

An embodiment of a computer-readable medium is described. The computermedium stores executable instructions that, when executed by aprocessor, cause the processor to perform a method for serving cachedweb content. The method includes caching, in a shared caching server, aversion of a web page that has a version identifier. The method furtherincludes receiving, at the shared caching server, a request from a userto access a current version of the web page. The user may be from one oftwo or more different user types, and users of different types receivedifferent versions of the web page. The method further includes sendinga validation request to an origin server. The validation requestincludes information indicative of the version identifier andinformation about the user. The method further includes receiving, atthe shared caching server, a response from the origin server thatincludes a modified version of the web page for sending to the user orincludes instructions to send the cached version of the web page to theuser. The response is generated by the origin server, based, at least inpart, on at least one of the set consisting of: a determination of theuser's user type and a determination as to whether the web page in theshared caching server is the current version of the web page. If amodified version of the web page is received by the shared cachingserver from the origin server, the method further includes providing themodified version of the web page to the user. If no modified version ofthe web page is received by the shared caching server, the methodfurther includes providing the cached version of the web page to theuser.

For purposes of describing the invention, certain aspects, advantagesand novel features of various embodiments of the invention have beendescribed herein. Of course, it is to be understood that not necessarilyall such aspects, advantages or features will be embodied in anyparticular embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements various features of specificembodiments of the invention will now be described with reference to thedrawings. The drawings and the associated descriptions are provided toillustrate embodiments of the invention and not to limit the scope ofthe invention. Throughout the drawings, reference numbers are re-used toindicate correspondence between referenced elements. In addition, thefirst digit of each reference number indicates the figure in which theelement first appears.

FIG. 1 is a block diagram depicting one embodiment of a system for thedynamic serving of content.

FIG. 2A depicts one embodiment of a web page format for web pages servedto a first type of user.

FIG. 2B depicts one embodiment of a web page format for web pages servedto a second type of user.

FIG. 3 is a flowchart that depicts one embodiment of a process forserving content by a shared caching server.

FIG. 4 is a flowchart that depicts one embodiment of a process fordirecting a shared caching server to serve content.

FIG. 5 is a block diagram depicting one embodiment of a computer serversystem configured to run software for implementing one or moreembodiments of the systems and methods for dynamic serving of contentdescribed herein.

DETAILED DESCRIPTION

Overview

One aspect of embodiments of the invention includes a recognition that,for some dynamic content servers that serve web pages to more than onetype of user (for example, a blog), the server may serve substantiallythe same dynamic content for the vast majority of users (for example, togeneral readers), but have additional and/or different content for justa few users, such as for one or more user types (for example, the blogowner, or a moderator of a forum). For example, some users may receiveadditional edit buttons or other controls on their page. Even those fewusers generally receive most of the same content with only partialchanges being made.

Another aspect of embodiments of the invention includes a recognitionthat web pages that are slightly (or otherwise partially) customized ona per-user-type basis may conventionally be recognized independentlybased on their differentiation, however slight, and may be independentlycached. Using such conventional methods, the cache process may beunderutilized due to constraints of the applied approach. Moreover,because many web pages are dynamic and/or partially customized, theirviewers and servers are not availed of the benefits of caching under theconventional approach described above, causing a round trip to theorigin server on every request and a subsequent recreation of eachdynamic page in full.

For example, for a given blog, most of the users receive the normal blogcontent. However, the blog owner receives slightly different contentwhen he or she accesses the blog because, for instance, he or she may beallowed to delete or edit entries or otherwise modify the blog in a wayunavailable to general readers. Similarly, a web forum may provide thesame content to a general public of most users, including in someinstances, an ability to add comments, but a few users, such asmoderators, receive slightly different pages because they have access totools, not available to normal users, that allow them to performfunctions related to moderating (for example, deleting posts). In thesesituations, it can be wasteful, in terms of system resources, toconstantly request the desired content from the dynamic content serverfor each user request, because most users receive the same content.

For high volume pages, these situations may represent approximately 99%of the web traffic, such that implementation of the systems and methodsdescribed herein can result in a reduction of the overall system load byan order of magnitude.

Embodiments of a system are described that utilize, at least in part,the use of Hypertext Transfer Protocol (HTTP) entity tags (ETags), orother appropriately configured revalidation headers (also known asvalidation headers). ETags are conventionally used to verify whether ornot a web page associated with the given ETag has changed. Inembodiments of systems and methods disclosed herein, the use of ETags,or other revalidation headers, is extended to further identify usertypes associated with web pages. ETags advantageously provide an abilityto include one or more character strings whose structure and/orinterpretation is not dictated by the HTTP protocol, but that can beconfigured as desired to suit the uses of systems in which they areused. As disclosed herein, the ETags can be used, in conjunction with anidentification of requests from various types of users, such as “owner”versus “reader” web page requests, for sending either a “modified”response or “not modified” response, as will be described in greaterdetail below.

Embodiments of a shared caching system, as described, can cache thecontent from these types of pages for at least one type of user. Forexample, the shared caching system may advantageously be used to cachecontent that is frequently requested and infrequently changed, such ascontent for blog readers. In some embodiments, content for one or moreuser types, such as content for blog owners, which may be accessedrelatively infrequently, but more often changed when accessed, may notbe cached by the shared caching server. Before serving the cached pagein response to a user request, the shared caching server can perform afast check with an origin server (for example, on every request) to seeif the current requestor is a type of user that can use the alreadycached page. More specifically, a check can be performed to identifycertain requestors (page owners, moderators, and so forth) who arelikely to get different content that differs from the generalpopulation. In various embodiments, the origin server can determine theuser type quickly through the use of cookies or other information aboutthe user, which may be obtained in conjunction with a user sign-inprocess. The origin server can serve, to the identified certainrequesters, content that is distinguished from the general population byserving the content in a customized form or by redirecting them todifferent pages altogether. Thus, the same URLs can appear to be fullydynamic to the end user, whether identified as a certain requestor orgeneral population user, even though the URL is actually being cached,and the system can handle a reasonable level of transparentpersonalization as well.

Embodiments of the systems and methods described herein help to reduceshared caching system loads for web content that is dynamic for only asmall portion of the people who view the web content. Furthermore, thesystems and methods can reduce the load on a dynamic content server byapplying caching that advantageously makes use of existing servingand/or caching infrastructure.

Although the present disclosure describes the systems and methods interms of embodiments that use the HTTP protocol, and ETags inparticular, it is to be understood that in other embodiments, othertransfer protocols may additionally or alternatively be used.Furthermore, although the use of ETags provides various benefits, inother embodiments, other forms of control/validation/revalidationheaders may be used in performing the methods and systems disclosedherein.

These improvements are more than trivial, as one of the problems withprior systems is an inability to handle problems specific to sharedcaching systems, such as the issues of partial modifications to webpages, which thwarted application of the conventional caching in ameaningful way. More particularly, local caching requires serverdelivery to each end user client, whereas a shared caching solutionwould be positioned upstream, saving the server from having to deliverto each client, even in situations where partial customization exists.

Sample Embodiment

FIG. 1 is a block diagram depicting one embodiment of a system 100comprising an origin server 150 and a shared caching server 140 that arein communication for providing dynamic content to users 110, 120 of twoor more different types. As one example, the dynamic content may be aweb log (blog) and the users may include at least one user 110 who is anowner of the blog and one or more users 120 who are readers of the blog.In response to a request to access the blog, the owner 110 may bepresented with a version of the blog that is slightly different from theversion presented to the readers 120. For example, in addition tocontent that is presented to the readers 120, the owner 110 may also bepresented with edit controls that allow the owner 110 to add blogcomments, delete blog comments, or the like.

In other embodiments, other types of users 110, 120 (such as, forexample, one or more moderators, administrators, site visitors, or thelike) may be served by the system 100. In some embodiments, there may bemultiple “owners” 110 for the dynamic content. In some embodiments, withor without an “owner” user type, the system 100 may be configured todifferentiate between readers of different types, such as members andnon-members of a web-based service, each type receiving contentdesignated for that user type. In some embodiments, more than twodifferent user types may be served by the system 100, wherein users fromeach user type receive content appropriate for that user type.

Requests from users 110, 120 to access the web content can be made via anetwork 130, such as the Internet's World Wide Web. In some embodiments,different users 110, 120 may use different networks 130 to access theweb content. A request from a user 110, 120 to access a web page isrouted via the network 130 to the shared caching server 140, which, asdepicted in the embodiment shown in FIG. 1, houses a cache of stored webpages 145. The request may identify a desired Uniform Resource Locator(URL) and may include identifying information about the user 110, 120,in the form of cookies. In some embodiments, more than one sharedcaching server 140 may be used for accessing and for distributing webcontent for users 110, 120. In some embodiments, some or all of thecache of stored web pages 145 may be stored internally or externallywith respect to the shared caching server 140.

The shared caching server 140 identifies whether a web page has beencached for the requested URL. As will be described with reference toFIGS. 2A and 2B, each cached web page includes an ETag header that canbe used to determine whether the cached web page is a most recentversion of the web page. As will also be described, the ETag furtheridentifies a type of user for which the stored web page is appropriate.

In response to the user request, the shared caching server 140 sends avalidation request to the origin server 150 in order to inquire whetherthe cached web page from the cache of stored web pages 145 should beserved to the requesting user or whether a modified page should beserved instead. The validation request includes some or all of the ETagfrom the identified cached web page, if a cached web page wasidentified, as well as information about the requested URL and cookieinformation about the user 110, 120 making the request. In someembodiments, if the shared caching server 140 identifies a cached webpage for the requested URL, the associated ETag information may beincluded in the validation request without additional information aboutthe requested URL.

The origin server 150 includes a store of current versions of web pages180 for the various types of users. A requestor identification module160 in the origin server 150 uses the cookie information or other userinformation to determine what is the user type of the user 110, 120 whois requesting the web page, such as for example using a look-up table orother data structure. The user type information is provided to anETag-based decision module 170. The ETag-based decision module 170includes logic for determining whether the identified cached web pagefrom the shared caching server 140 may be server to the user 120 orwhether a more current, modified copy of the requested web page 180 isto be forwarded to the shared caching server 140 in response to the userrequest.

A sample determination is now described using the example depicted inFIG. 1, in which Type A users 110 are web page owners and Type B users120 are web page readers. The ETag-based decision module 170 can beconfigured to determine, in response to a request from a reader 120(Type B), that if the received ETag matches the most recent version ofthe web page, then the cached web page in the shared caching server 140can be provided to the reader 120. In this case, the origin server 150can send a response message to the shared caching server 140,instructing the shared caching server 140 to use the cached web page.If, instead, the ETag-based decision module 170 determines that thereceived ETag does not match the most recent version of the web page,then an updated version of the web page, with an appropriately updatedETag, can be sent to the shared caching server 140 for providing to thereader 120 and, in some embodiments, for replacing the cached version ofthe web page in the repository of cached web pages 145.

In the embodiment depicted in FIG. 1, if the user is identified as beingan owner 110 (Type A), the ETag-based decision module 170 may beconfigured to send a new version of the web page to the shared cachingserver 140, whether the ETag indicates that the cached version is acurrent version or not. Furthermore, as will be described with referenceto FIGS. 2A and 2B below, the shared caching server 140 may beinstructed not to cache the owner version of the web page.

In short, in at least one embodiment, as summarized in Table 1 below,the origin server 150 sends a response that indicates that the contentfrom the cache 145 is stale (and should be replaced) if the page isbeing accessed by the owner 110. However if the page is being accessedby a reader 120, the response depends on whether or not a more currentversion of the web page exists in the origin server's 150 store of webpages 180.

TABLE 1 Sample Etag-Based Logic PAGE MODIFIED PAGE NOT MODIFIED READERSend page modified response Send page not modified response OWNER Sendpage modified response Send page modified response

As will be understood by one of ordinary skill in the art, in light ofthe present disclosure, in other embodiments with other user types, theEtag-based decision module 170 may comprise other logic to determinewhether to send an current modified version 180 of the requested webpage or to instruct the shared caching server 140 to serve the cachedpage from the repository 145.

Thus, the shared caching server 140 may store current copies of readerweb pages, for which requests may arrive relatively frequently over thenetwork and which are changed relatively rarely between requests. Insome embodiments, the shared caching server 140 does not store copies ofowner web pages, which may be requested relatively rarely and mayfrequently be changed at each request. Efficient use of the sharedcaching server 140 is thus enhanced.

Use of Etags

FIGS. 2A and 2B depict embodiments of web page formats 200, 250 for webpages served to different user types 110, 120 in accordance with thesystems and methods disclosed herein. In particular, FIGS. 2A and 2Bdepict embodiments of web page formats 200, 250 for use in conjunctionwith the sample embodiment depicted in FIG. 1. FIG. 2A depicts oneembodiment of a web page format 200 for a web page to be viewed by areader 120, and FIG. 2B depicts one embodiment of a web page format 250for a web page to be viewed by an owner 110.

Both of the web page formats 200, 250 include one or more controlheaders 210 a, 210 b that provide instructions to the shared cachingserver 140 for processing the web pages. Some shared caching servers 140can use an “age” header on a cached object to determine how long thecached object is to be considered “fresh” and suitable for serving torequestors. The sample control headers 210 a, 210 b in FIGS. 2A and 2Binclude a “max-age=0” header that indicates to the shared caching server140 that there is no length of time for which the web page can beguaranteed to be valid. With this header, the shared caching server 140is thereby instructed to check the validity of the cached web page uponeach request for the page. The depicted sample control header 210 a forthe reader page further includes instructions that the cached web pageis to be re-validated by the origin server 150 upon each user requestand before providing the cached web page to the user 110, 120. Thesample control header 210 b for the owner page depicted in FIG. 2Bfurther instructs the shared caching server 140 that the web page shouldnot be cached.

In other embodiments, other control headers may additionally oralternatively be used with the web page formats 200, 250, or other webpage formats, such as to allow for the inclusion of multiple sharedcaching servers 140 in the system 100 and/or for other types of cachesor servers. For example, a “proxy-revalidate” control header and/or a“Pragma: no-cache” control header may be used. Other control headers mayadditionally or alternatively be used for other reasons, such as toaccommodate compatibility with earlier versions of caching protocols.

More information on cache-control headers that may be used withembodiments of the systems and methods described herein can be found inInternet Engineering Task Force (IETF) Request for Comments (RFC) number2616, section 14.9.

Both of the example web page formats 200, 250 include an ETag 220 a, 220b, which is a type of revalidation header. In various embodiments, thecontent of the ETag 220 a, 220 b is unique for each version of the webpage and also depends, at least in part, on one or more user types forwhom the web page is intended. For example, in various embodiments, theweb page may be one that is served for most readers, or the owner, themoderator, and so forth.

The ETags 220 a, 220 b depicted in FIGS. 2A and 2B include a beginningnumerical portion on the left-hand side that can be a coded time-stamp,frequently expressed in milliseconds, for indicating a time at which theweb page was last modified. The time-stamp in the ETag 220 a, 220 b sentby the shared caching server 140 can be used by the ETag-based decisionmodule 170 to compare with a time-stamp on the current version of theweb page in the origin server 150 in order to determine if the cachedweb page is a current version of the requested web page.

The ETags 220 a, 220 b depicted in FIGS. 2A and 2B, which are suitable,for example, for blog web pages, also include an indication, at theright-hand side, of a number of comments that are included in theversion of the web page associated with the ETag. The indication, whichmay be referred to herein as a comment-counter, may be encoded, forexample, as “C=x” where “x” is equal to the number of comments in theweb page. The ETags 220 a, 220 b in FIGS. 2A and 2B indicate that theversion of the sample web page has one comment. Information about thenumber of comments in the web page may be used as another way to use theETag 220 a, 220 b to compare the currency of a cached web page with thecurrent version of the web page as stored in the origin server 150.

In addition to the time-stamp and the comment-counter, the ETag 220 bfor an owner web page may also include a user-type-indicator, which inFIG. 2B is depicted as the character string “ow:” interposed between thetime-stamp and the comment-counter. The lack of the character string“ow:” in the ETag 220 a for the reader web format 200 can indicate thatthe page is not intended for serving to an owner 110. Thus, embodimentsof the ETag 220 a, 220 b include user-type identification information inaddition to information that allows for comparison with a currentversion of the web page.

The web page formats 200, 250 in FIGS. 2A and 2B further include webpage content 230 a, 230 b that may be personalized for the type of user.For example, as previously described, the web page content 230 b for anowner page may include edit controls or other features not provided toreaders 120 accessing the web page. It is recognized that a variety ofweb page formats may be used.

As will be understood by practitioners of ordinary skill in the art inlight of the present disclosure, in other embodiments, other methods mayadditionally or alternatively be used to differentiate between a pagethat needs to be refreshed and one that can be served as cached usingone or more ETags or other validation headers. As one example, cookieheaders can be used as validation headers. In at least one embodiment,the shared caching server 140 appends the validation informationdescribed herein with reference to Etags in the form of a cookie for thevalidation request. The validation information may include, for example,user type, version information, date of last update, or the like.

In some embodiments, the shared caching server 140 is configured tocache web pages that have time set to 0, and also include an ETag 220 a,220 b and other cache headers 210 a, 210 b. The caching server thereforecaches the received web page, and does not serve it up to a user 110,120 without revalidating the web server. When the caching server 140receives another request for the web page, the caching server 140 triesto validate the web page by sending the ETag and a Conditional GETrequest to the origin server 150. If the Conditional GET request is forthe same version of the web page that is currently cached (and, usingthe current example, if the user-type is reader 120), the ETags are thesame. The origin server 150 may indicate that the web page versions arethe same and may not return any content, in which case, the sharedcaching server 140 serves the version from the cache 145 to therequestor. Otherwise, if the ETag 220 a, 220 b and other validationrequest information indicate that the cached page is not the currentversion and/or that the user type for the request is one that alwaysgets a new version of the web page (such as the “owner” type in ourexample), the origin server 150 returns a new version of the requestedweb page to the shared caching server 140. In some embodiments,appropriate headers can be set so that the shared cached server 140caches a reader-version web page and does not cache an owner-version webpage.

While the use of ETags with respect to caching systems has been knownfor validating the “freshness” of cached data, the inclusion of usertype information within the ETag allows the systems and methodsdisclosed herein to use existing caching and serving infrastructure toreduce load on an origin server 150 that serves dynamic content to aplurality of user types.

Operation

FIG. 3 is a flowchart that depicts one embodiment of a process 300 forserving content by a shared caching server 140. The process 300 beginsin state 310, in which the shared caching server 140 receives a userrequest to access a web page. In various embodiments, the user requestmay include information about a desired web page and informationindicative of a user who is requesting the web page.

In state 320, the shared caching server 140 determines if a cachedversion of the requested web page is available in the repository ofcached web pages 145. Once the shared caching server 140 determines if acached version of the requested web page is available, the sharedcaching server 140 sends a validation request to the origin server 150.

If no cached version of the requested web page is available, thevalidation request includes information about the requested web page andinformation about the user, as indicated in state 330. If a cachedversion of the requested web page is available, as indicated in state340, the shared caching server 140 sends a validation request thatincludes ETag information from the cached version of the web page, aswell as information about the user making the request. In someembodiments, additional information about the requested web page isincluded in the validation request. In other embodiments, theinformation about the requested web page is included in the ETaginformation.

From state 330 or state 340, the process 300 continues to state 350,where the shared caching server receives instructions from the originserver 150 in response to the validation request. In particular, asdepicted in state 360, the shared caching server 140 determines if theorigin server 150 has sent an updated version of the web page inresponse to the request.

If the origin server 150 has not sent an updated version of the web pagein response to the request, then the cached web page identified by theshared caching server is appropriate for the user type of the requestorand is an up-to-date version of the page. In state 370, the sharedcaching server can serve the web page to the requesting user.

Alternatively, if the original server 150 has sent an updated version ofthe web page in response to the request, then the cached web pageidentified by the shared cashing server 140, if any, is not appropriatefor the user type of the requestor and/or is not an up-to-date versionof the page. In state 380, the shared caching server can serve themodified web page to the requesting user. Furthermore, as depicted instate 390, if the modified web page received by the shared cachingserver 140 is cacheable, the shared caching server 140 may store themodified web page in the repository of cached web pages 145 for use withrespect to future user requests.

FIG. 4 is a flowchart that depicts one embodiment of a process 400 fordirecting the shared caching server 140 to serve content.

Beginning in state 410, the origin server 150 receives a web pagevalidation request from the shared caching server 140. The validationrequest includes, among other types of information, information that isindicative or that can be used by the origin server 150, in state 420,to ascertain the user type of the user who is requesting the web page.For example, the validation request may include a name or identifierassociated with the user, which the requestor identification module 160of the origin server 150 may use to access stored information about theuser type associated with the user. Additionally or alternatively, thevalidation request itself may include information about the requestor'suser type, either with or without additional information about theidentity of the requester.

In state 430, the ETag-based decision module 170 determines, based onthe requestor's user type identified in state 420 and on the ETag usertype information, whether the cached web page is appropriate for therequestor.

If the cached web page is appropriate for the requester, in state 440,the ETag-based decision module 170 further determines, again based onthe ETag information, whether the cached web page is a current version.For example, as described with reference to FIGS. 2A and 2B, ETagtime-stamp information, ETag comment-counter information and/or othertypes of information included in the ETag may be used to determine thecurrency of the cached web page.

If, in state 440, the ETag-based decision module 170 determines that thecached web page is a current version, then in state 450, the originserver 150 can instruct the shared caching server 150 to serve thecached web page to the requesting user.

If, in state 430, the origin server 150 determines that the cached webpage is not appropriate for the requestor's user type, or, if, in state440, the ETag-based decision module 170 determines that the cached webpage is not a current version, then the process 400 moves to state 460,in which the origin server 150 sends a current version of the web page,with an appropriately updated ETag, to the shared caching server 140. Bysending the current version of the web page, the origin server 150indicates to the shared caching server 140 that the previously cachedweb page is not appropriate for serving to this requestor.

As will be familiar to practitioners of ordinary skill in the art inlight of the present disclosure, other embodiments of the processes 300,400 described in FIGS. 3 and 4 may be carried out by executing thefunctions described in FIGS. 3 and/or 4 in a different order, bydividing the functions in another manner, and/or by including some orall of the functions described above in conjunction with otherassociated functions.

System

FIG. 5 is a block diagram depicting one embodiment of a computer serversystem 500 configured to run software for implementing one or moreembodiments of the systems and methods for dynamic serving of contentdescribed herein. The shared caching server 140 and/or the origin server150 may be implemented using one or more physical machines, as describedwith reference to FIG. 5, and the functions described with respect tothe shared caching server 140 and/or the origin server 150 may beimplemented using one or more software components. The computer serversystem(s) 500 may include a central processing unit (CPU) 504, which mayinclude one or more conventional microprocessors. The computer serversystem(s) 500 may further include a memory 505, such as random accessmemory (“RAM”) for temporary storage of information and a read onlymemory (“ROM”) for permanent storage of information, and a mass storagedevice 501, such as a hard drive, diskette, or optical media storagedevice.

The computer server system(s) 500 may include one or more commonlyavailable input/output (I/O) devices and interfaces 503, such as akeyboard, mouse, touchpad, microphone, and printer. Thus, in oneembodiment, the computer server system(s) 500 may be controlled usingthe keyboard and mouse input devices, while in another embodiment, theuser may provide voice commands to the computing device via amicrophone. In one embodiment, the I/O devices and interfaces 503include one or more display devices, such as a monitor, that allows thevisual presentation of data to a user, such as a system administrator.More particularly, a display device provides for the presentation ofGUIs, application software data, and multimedia presentations, forexample. The computer server system(s) 500 may also include one or moremultimedia devices 502, such as speakers, video cards, graphicsaccelerators, and microphones, for example.

In one embodiment, the I/O devices and interfaces 503 provide acommunication interface to various external devices. For example, thecomputer server system(s) 500 may be configured to communicate with oneor more networks, such as any combination of one or more LANs, WANs, orthe Internet, for example, via a wired, wireless, or combination ofwired and wireless, communication links. The network communicates withvarious computing device, including user computing devices and/or otherelectronic devices via wired or wireless communication links. In oneembodiment, the user computing devices may be IBM, Macintosh, and/orLinux/Unix compatible. In various embodiments, the user computingdevices may comprise one or more servers, laptop computers, cell phones,Blackberry devices, personal digital assistants, kiosks, or audioplayers, for example.

The computer server system(s) 500 may further comprise a content servingmodule 506 that manages the functions for serving and caching of dynamiccontent for access by users of two or more different user types. Whenthe computer system 500 is an origin server 150, an embodiment of whichis described with reference to FIG. 1, the content serving module 506may store and/or carry out, among other functions disclosed herein, anembodiment of the process 400 for directing the shared caching server140 to serve content, as described with reference to FIG. 4. When thecomputer system 500 is a shared caching server 140, an embodiment ofwhich is described with reference to FIG. 1, the content serving module506 may store and/or carry out, among other functions disclosed herein,an embodiment of the process 300 for serving content, as described withreference to FIG. 3.

Typically, modules of the computer server system(s) 500 areelectronically connected using a standards based bus system. Indifferent embodiments, the standards based bus system could bePeripheral Component Interconnect (PCI), Microchannel, SCSI, IndustrialStandard Architecture (ISA) and Extended ISA (EISA) architectures, forexample. In certain embodiments, components of the computing devicecommunicate via a network, such as a local area network that may besecured.

The shared caching server 140 and/or the origin server 150 are generallycontrolled and coordinated by operating system software, such as Windows95, Windows 98, Windows NT, Windows 2000, Windows XP, Windows Vista,Linux, SunOS, Solaris, or other compatible operating systems. InMacintosh systems, the operating system may be any available operatingsystem, such as MAC OS X. In other embodiments, the servers 140, 150 maybe controlled by a proprietary operating system. Conventional operatingsystems control and schedule computer processes for execution, mayperform memory management, provide file system, networking, and I/Oservices, and may provide an interface, such as a graphical userinterface (“GUI”), among other things.

In various embodiments, the systems and methods for caching and servingdynamic content may be embodied in part or in whole in software that isrunning on one or more computer server systems 500. The functionalityprovided for in the components and modules of the computer serversystem(s) may comprise one or more components and/or modules.

In general, the word “module,” “application”, or “engine,” as usedherein, refers to logic embodied in hardware and/or firmware, and/or toa collection of software instructions, possibly having entry and exitpoints, written in a scripting or programming language, such as, forexample, PHP, Python, .NET (DotNet), ASP, Java, Ruby, Ruby on Rails,Lua, C and/or C++. These may be compiled and linked into an executableprogram, installed in a dynamic link library, or may be written in aninterpreted programming language such as, for example, BASIC, Perl, orPython. It will be appreciated that modules, applications, and enginesmay be callable from others and/or from themselves, and/or may beinvoked in response to detected events or interrupts. Instructions maybe embedded in firmware, such as an EPROM.

It will be further appreciated that hardware may be comprised ofconnected logic units, such as gates and flip-flops, and/or may becomprised of programmable units, such as programmable gate arrays orprocessors. The modules, applications, and engines described herein arein certain applications preferably implemented as software modules, butmay be represented in hardware or firmware in other implementations.Generally, the modules, applications, and engines described herein referto logical modules that may be combined with other modules and/ordivided into sub-modules despite their physical organization or storage.

In some embodiments, the computer server system(s) 500 may communicatewith one or more databases that store information, including userinformation, dynamic content storage information, and the like. Thisdatabase or databases may be implemented using a relational database,such as SQLite, Sybase, Oracle, CodeBase, mySQL, and Microsoft® SQLServer as well as other types of databases such as, for example, a flatfile database, an entity-relationship database, and object-orienteddatabase, and/or a record-based database.

Additional Embodiments

Although the foregoing invention has been described in terms of certainembodiments, other embodiments will be apparent to those of ordinaryskill in the art from the disclosure herein. Moreover, the describedembodiments have been presented by way of example only, and are notintended to limit the scope of the inventions. Indeed, the novel methodsand systems described herein may be embodied in a variety of other formswithout departing from the spirit thereof. Accordingly, othercombinations, omissions, substitutions and modifications will beapparent to the skilled artisan in view of the disclosure herein. Thus,the present invention is not intended to be limited by the preferredembodiments. Furthermore, for purposes of discussing the invention,certain aspects, advantages and novel features of the invention havebeen described herein. Of course, it is to be understood that notnecessarily all such aspects, advantages or features will be embodied inany particular embodiment of the invention.

For example, in some embodiments, web pages for owners 110, as well asweb pages for readers 120 are cached in the shared caching server 140.When a request from a user 110, 120 is received by the shared cachingserver 140, the shared caching server 140 uses a look-up table or otherlocator information to determine if any versions of the web page arestored in the cache of stored web pages 145. The shared caching server140 may send a validation request that includes ETags 220 a, 220 b fromany web pages identified, possibly including web pages for differentuser types, as well as user information. The requestor identificationmodule 160 determines the user type, and the ETag-based decision module170 determines (a) whether any of the ETags received from the sharedcaching server 140 correspond to the user type, and (b) if so, if theETag corresponds a current version of the web page for that user type.The origin server 150 can then respond to the shared caching server 140with instructions as to which of the cached pages, if any, to send tothe user, or with instructions that include a modified web page forsending to the user and for storing in the cache of stored web pages 145as a current web page for that type of user.

As another example, in some embodiments, the requestor identificationmodule 160, described as being part of the origin server 150, mayadditionally or alternatively be configured to reside in the sharedcaching server 140. The shared caching server 140 may therefore be ableto determine a requestor's user type and may configure and/or send thevalidation request accordingly.

Additionally, although the content being served has been describedherein as being web pages, in other embodiments, other types of contentmay additionally or alternatively be served using the disclosed systemsand methods.

1. A computer-implemented method of serving web content with a cacheserver, the method comprising: storing a cached version of a web page inmemory, the cached version of the web page reflecting a version of theweb page as of a particular time or date; receiving a request from aclient for a version of the web page; sending a validation request to anorigin server, the origin server storing a current version of the webpage that reflects a version of the web page that has been modifiedsince the particular date or time of the cached version of the web page;receiving a validation response from the origin server, wherein: if theclient is associated with a first category of clients for which cachedversions of web pages are to be served, the validation response includesan instruction for the cache server to provide the cached version of theweb page to the client; and if the client is associated with a secondcategory of clients for which current versions of web pages are to beserved, the validation response includes the current version of the webpage and an instruction for the cache server to provide the currentversion of the web page to the client; and providing the cached versionof the web page or the current version of the web page to the clientaccording to the validation response.
 2. The method of claim 1, whereinthe validation request includes information indicating the particulartime or date associated with the cached version of the web page.
 3. Themethod of claim 2, wherein the validation request includes informationindicative of a client type.
 4. The method of claim 3, furthercomprising: determining the client type based on cookie informationincluded in the request from the client.
 5. The method of claim 1,wherein the validation request includes an ETag that includesinformation indicating the particular time or date associated with thecached version of the web page.
 6. The method of claim 5, wherein theETag includes information indicative of a client type.
 7. The method ofclaim 5, further comprising: receiving a validation response thatincludes the current version of the web page and an instruction toprovide the current version of the web page to the client, wherein thecurrent version of the web page received from the origin server includesa new ETag that includes information indicating a particular date ortime associated with the current version of the web page; providing thecurrent version of the web page to the client; and using the currentversion of the web page received from the origin server as the cachedversion of the web page.
 8. The method of claim 1, wherein the secondcategory of clients comprises clients with ownership rights to contentassociated with the web page, and wherein the first category of clientscomprises clients without ownership rights to content associated withthe web page.
 9. The method of claim 1, wherein the second category ofclients comprises members of a web-based service associated with the webpage, and wherein the first category of clients comprises non-members ofthe web-based service associated with the web page.
 10. Acomputer-implemented method of serving web content with an originserver, the method comprising: providing a cached version of a web pageto a cache server, the cached version of the web page reflecting aversion of the web page as of a particular time or date; storing acurrent version of the web page in memory, wherein the current versionof the web page represents a version of the web page that has beenmodified since the particular date or time of the cached version of theweb page; receiving a validation request from the cache server, whereinthe validation request includes information about a client requesting aversion of the web page from the cache server; determining whether theclient is associated with a first category of clients or a secondcategory of clients, wherein the first category of clients representsclients for which cached versions of web pages are to be served and thesecond category of clients represents clients for which current versionsof web pages are to be served; sending a validation response to thecache server, wherein: if the client is associated with the firstcategory of clients, the validation response includes an instruction forthe cache server to provide the cached version of the web page to theclient; and if the client is associated with the second category ofclients, the validation response includes the current version of the webpage and an instruction for the cache server to provide the currentversion of the web page to the client.
 11. The method of claim 10,wherein the validation request includes information indicating theparticular time or date associated with the cached version of the webpage.
 12. The method of claim 11, wherein the validation requestincludes information indicative of a client type, and wherein the originserver determines whether the client is associated with the firstcategory of clients or the second category of clients using theinformation indicative of the client type.
 13. The method of claim 10,wherein the validation request includes an ETag that includesinformation indicating the particular time or date associated with thecached version of the web page.
 14. The method of claim 13, wherein theETag includes information indicative of a client type, and wherein theorigin server determines whether the client is associated with the firstcategory of clients or the second category of clients using theinformation indicative of the client type.
 15. The method of claim 10,wherein providing the cached version of the web page to the cache serverfurther comprises: providing the cached version of the web page alongwith an ETag that indicates the particular time or date associated withthe cached version.
 16. The method of claim 15, further comprising:sending a validation response to the cache server that includes thecurrent version of the web page along with an ETag that includesinformation indicating a particular date or time associated with thecurrent version of the web page.
 17. The method of claim 10, wherein thesecond category of clients comprises clients with ownership rights tocontent associated with the web page, and wherein the first category ofclients comprises clients without ownership rights to content associatedwith the web page.
 18. The method of claim 10, wherein the secondcategory of clients comprises members of a web-based service associatedwith the web page, and wherein the first category of clients comprisesnon-members of the web-based service associated with the web page.
 19. Acache server, comprising: a processing system comprising one or moreprocessors; and a memory system comprising one or more non-transitorycomputer-readable media containing instructions that, when executed bythe processing system, cause the cache server to perform operationscomprising: storing a cached version of a web page in memory, the cachedversion of the web page reflecting a version of the web page as of aparticular time or date; receiving a request from a client for a versionof the web page; sending a validation request to an origin server, theorigin server storing a current version of the web page that reflects aversion of the web page that has been modified since the particular dateor time of the cached version of the web page; receiving a validationresponse from the origin server, wherein: if the client is associatedwith a first category of clients for which cached versions of web pagesare to be served, the validation response includes an instruction forthe cache server to provide the cached version of the web page to theclient; and if the client is associated with a second category ofclients for which current versions of web pages are to be served, thevalidation response includes the current version of the web page and aninstruction for the cache server to provide the current version of theweb page to the client; and providing the cached version of the web pageor the current version of the web page to the client according to thevalidation response.
 20. The system of claim 19, wherein the validationrequest includes information indicating the particular time or dateassociated with the cached version of the web page.
 21. The system ofclaim 20, wherein the validation request includes information indicativeof a client type.
 22. The system of claim 21, wherein the memory systemfurther includes instructions for: determining the client type based oncookie information included in the request from the client.
 23. Thesystem of claim 19, wherein the validation request includes an ETag thatincludes information indicating the particular time or date associatedwith the cached version of the web page.
 24. The system of claim 23,wherein the ETag includes information indicative of a client type. 25.The system of claim 23, wherein the memory system further includesinstructions for: receiving a validation response that includes thecurrent version of the web page and an instruction to provide thecurrent version of the web page to the client, wherein the currentversion of the web page received from the origin server includes a newETag that includes information indicating a particular date or timeassociated with the current version of the web page; providing thecurrent version of the web page to the client; and using the currentversion of the web page received from the origin server as the cachedversion of the web page.
 26. The system of claim 19, wherein the secondcategory of clients comprises clients with ownership rights to contentassociated with the web page, and wherein the first category of clientscomprises clients without ownership rights to content associated withthe web page.
 27. The system of claim 19, wherein the second category ofclients comprises members of a web-based service associated with the webpage, and wherein the first category of clients comprises non-members ofthe web-based service associated with the web page.
 28. An originserver, comprising: a processing system comprising one or moreprocessors; and a memory system comprising one or more non-transitorycomputer-readable media containing instructions that, when executed bythe processing system, cause the cache server to perform operationscomprising: providing a cached version of a web page to a cache server,the cached version of the web page reflecting a version of the web pageas of a particular time or date; storing a current version of the webpage in memory, wherein the current version of the web page represents aversion of the web page that has been modified since the particular dateor time of the cached version of the web page; receiving a validationrequest from the cache server, wherein the validation request includesinformation about a client requesting a version of the web page from thecache server; determining whether the client is associated with a firstcategory of clients or a second category of clients, wherein the firstcategory of clients represents clients for which cached versions of webpages are to be served and the second category of clients representsclients for which current versions of web pages are to be served;sending a validation response to the cache server, wherein: if theclient is associated with the first category of clients, the validationresponse includes an instruction for the cache server to provide thecached version of the web page to the client; and if the client isassociated with the second category of clients, the validation responseincludes the current version of the web page and an instruction for thecache server to provide the current version of the web page to theclient.
 29. The system of claim 28, wherein the validation requestincludes information indicating the particular time or date associatedwith the cached version of the web page.
 30. The system of claim 29,wherein the validation request includes information indicative of aclient type, and wherein the origin server determines whether the clientis associated with the first category of clients or the second categoryof clients using the information indicative of the client type.
 31. Thesystem of claim 28, wherein the validation request includes an ETag thatincludes information indicating the particular time or date associatedwith the cached version of the web page.
 32. The system of claim 31,wherein the ETag includes information indicative of a client type, andwherein the origin server determines whether the client is associatedwith the first category of clients or the second category of clientsusing the information indicative of the client type.
 33. The system ofclaim 28, wherein providing the cached version of the web page to thecache server further comprises: providing the cached version of the webpage along with an ETag that indicates the particular time or dateassociated with the cached version.
 34. The system of claim 33, whereinthe memory system further includes instructions for: sending avalidation response to the cache server that includes the currentversion of the web page along with an ETag that includes informationindicating a particular date or time associated with the current versionof the web page.
 35. The system of claim 28, wherein the second categoryof clients comprises clients with ownership rights to content associatedwith the web page, and wherein the first category of clients comprisesclients without ownership rights to content associated with the webpage.
 36. The method of claim 28, wherein the second category of clientscomprises members of a web-based service associated with the web page,and wherein the first category of clients comprises non-members of theweb-based service associated with the web page.
 37. Acomputer-implemented method, the method comprising: storing a cachedversion of a web page in memory, the cached version of the web pagereflecting a version of the web page as of a particular time or date;receiving a request from a client for a version of the web page;determining whether the client is associated with a first category ofclients or a second category of clients, wherein the first category ofclients represents clients for which cached versions of web pages are tobe served and the second category of clients represents clients forwhich current versions of web pages are to be served; if the client isassociated with the first category of clients, providing the cachedversion of the web page to the client; and if the client is associatedwith the second category of clients, providing a current version of theweb page to the client, wherein the current version of the web pagerepresents a version of the web page that has been modified since theparticular date or time of the cached version of the web page.